In aerospace applications, various operating machines or mechanisms, such as blowers or engines or the like, require the scavenging of oil or cooling fluids from all attitudes of the apparatus. This often is accomplished by a plurality of pumps, such as impeller pumps, fluid jet pumps or the like, which are located at various positions on the apparatus for scavenging oil from internal cavities in the casing or housing of the apparatus. Multiple pumps are required because the apparatus will attain different attitudes during flight, for instance. A single pump might draw air instead of oil at one attitude or another.
An example of such use of scavenging systems in aerospace applications is in a blower for an air particle separator on a turbine engine. Particles or foreign matter often are encountered, such as sand in desert environments or other debris. The turbine engine blades throw the air and particles outwardly by centrifugal force to a chamber, commonly called a "scroll", surrounding the turbine blades. The blower draws the air and particles from the scroll and evacuates the mixture to atmosphere. Because of the blower's aerodynamic configuration, scavenging of oil from the blower requires at least two inlets so that the housing does not become flooded at a given attitude.
Heretofore, scavenging systems for blowers or other apparatus of the character described above provided a separate pump for each of the inlets. Check valves then would be incorporated in the system so that the pumps do not try to draw air and oil simultaneously. Since the pumps are designed into the housing or casing for the blower, it often becomes difficult to provide check valves at various desired locations. It is readily apparent that such pump and valve systems not only can be complicated to design for a particular blower application, but weight and cost considerations often have to be ignored.
This invention is directed to solving one or more of the above problems by providing a dual pump of a substantially unitary construction and including separate pump means each dedicated to its own inlet and interconnected for scavenging oil from the blower at various attitudes.